Symptom: "Sorry, You Are Not Allowed to Access This Page" when trying to access /wp-admin/update-core.php page to update your Wordpress site.
Cause: Page has been hacked and your wp_config file was modified.
Fix: Edit your wp_config page and remove the following statements.
define('DISALLOW_FILE_EDIT', true);
define('DISALLOW_FILE_MODS', true);
